【摘要】 报道1例进展期假性剥脱性青光眼中的Charles Bonnet综合征。方法：病例报告。结果：一例92岁的马来男性诉2a前出现幻视，并加重2mo。称看见成人及百余儿童生动活泼地出现在不同场合。他甚至有几次看见一只兔子偶尔跑过他的房间。但是，他觉察到这是一种异常的经历。与同年龄人相比，他的认知功能是正常的。精神病学评估包括精神状态检查是正常的。他曾经被诊断患有开角型青光眼，左眼以前接受过常规的白内障手术和小梁切除术。其视力为右眼手动，左眼6/7.5(0.8)伴管状视野。眼底镜检查显示左眼进行性青光眼性视杯加深。目前诊断为右眼大泡性角膜病变合并绝对期青光眼，左眼进展期假性剥脱性青光眼，有功能性滤过泡。结论：对诉有幻视的老年患者，特别是在痴呆和精神病的诊断标准不明确的情况下，诊断通常是很困难的。如果这些患者洞察到不复存在的东西进入其视觉范围，并伴有视觉功能恶化，应高度怀疑患有Charles Bonnet综合征的可能。
【关键词】 Charles Bonnet综合征 幻视
INTRODUCTION
Charles Bonnet syndrome[1] is a widely underrecognized disorder typically characterized by the occurrence of complex visual hallucinations in the presence of normal cognition in elderly individuals. It commonly happens following conditions where there has been a profound loss of vision or interruption of visual input into the occipital cortex. It is important to distinguish this largely innocuous condition from psychiatric conditions that exist in the same age group.
The visual hallucinations associated with this syndrome are usually complex and wellformed. It is also described as stereotyped, which involves animals, human or figures and usually in a dramatic and chromatic setting[2]. The visions were usually sharp and the frequency of hallucinations varied between daily and weekly while the duration was usually few minutes[3].
We reported a case of an elderly patient with underlying visual impairment presented with Charles Bonnet syndrome.
CASE REPORT
A 92yearold Malay man presented visual hallucination for 2 years with worsening of his symptoms for the past 2 months. He claimed that he had seen many people as well as hundreds of children on separate occasions vividly. He even saw a rabbit running across his room on a few occasions.
His visual hallucination usually occurs at night. He was afraid of these hallucinations initially and got used to it eventually, although he still felt uncomfortable with it. However, he had insight that this was an abnormal experience. Apart from this, there was no hallucination of other sensory modalities. He was able to take care of his personal hygiene and perform his daily routine activities.
He was diagnosed to have open angle glaucoma for more than 15 years. He also underwent left cataract surgery and trabeculectomy then. He was followed up by a private ophthalmologist a few years back. He was not on any topical antiglaucoma agents for more than 2 years.
Psychiatric evaluation showed that he was wellorientated, calm, forthcoming and euthymic. His speech was relevant and coherent. Mental State Examination was normal for his age. There was no memory impairment noted and his remote and recent memories were good. His neurological examination and systemic examination were unremarkable.
The visual acuity in the right eye was hand movement (HM) and the right eye was 6/7.5 with tunnel vision. Ocular examination of the right eye showed cornea bedewing with pseudoexfoliative materials at the pupillary margin (Figure 1). There was also presence of iris neovascularization with hyphema and mildly swollen cataractous lens. The left eye showed a formed shallow filtering bleb with a patent peripheral iridectomy and fairly controlled intraocular pressure (Figure 2). His intraocular pressure was 54mmHg in the right eye and 21mmHg in the left eye respectively. There was no fundus view of the right eye. Funduscopy of the left eye showed an advanced glaucomatous optic disc cupping (Figure 3).
Patient was diagnosed to have Charles Bonnet syndrome when presented the occurrence of complex visual hallucinations and nearly blindness in both eyes due to advanced glaucoma. The psychiatric evaluation was perfectly normal. He had right bullous keratopathy with absolute glaucoma and left advanced pseudoexfoliative glaucoma with a functioning bleb.
He started on topical Latanoprost in the left eye and topical Dorzolamide in the right eye. Topical steroid and cycloplegic were also added to the right eye. He was on regular followup by the psychiatrist to monitor the progress of the condition. After a few sessions of counseling, he felt more relieved and his symptoms were less bothering.
DISCUSSION
Elderly patient who presented visual hallucination often poses a diagnostic dilemma especially when the criteria for diagnosis of dementia and psychosis are not conclusive[2]. We reported an elderly patient with advanced glaucoma who presented Charles Bonnet syndrome. Although the prevalence of Charles Bonnet syndrome in patients with visual impairment was cited as varying from 10% to 15% in western population[3,4], the prevalence of this syndrome in an Asian population attending tertiary ophthalmic centre was cited as 0.4%[5], which is much lower in comparison. The lower prevalence among Asian population might be due to the fact that Asian people are more reserved in disclosing this phenomenon for fear of being stigmatized as mentally insane.
Although there were no universally approved diagnostic criteria for this syndrome, psychosis, impaired sensorium, dementia, intoxication, metabolic derangement and focal neurological illness must first be excluded[6]. The following diagnostic criteria[7] are accepted by most authorities: the presence of formed, complex, persistent or repetitive, stereotypical visual hallucinations; and full or partial retention of insight into the unreal nature of the hallucinations; and absence of hallucinations in other sensory modalities; and absence of primary or secondary delusions.
Patients with this syndrome often described varied visual hallucinations of figures, human or animals which present in variable sizes. These complex hallucinations are always outside the body and may last from a few seconds to most of the day. It was observed that these hallucinations usually do not bear any personal meaning and the patients can voluntarily make the image disappear by closing their eyes[2,3].
The pathogenesis is unclear although sensory deprivation and the reaction of the visual cortex to the sudden or progressive lack of visual stimulation which results in release phenomenon had been implicated (deafferentation hypothesis)[810]. Other authors further postulated that the dynamic decrease in visual acuity bears a greater impact than in chronic condition of low visual acuity in the development of Charles Bonnet syndrome[11].
The course, prognosis and treatment vary with the nature of the visual dysfunction. Some patients find the removal of underlying cause of visual impairment such as cataract extraction leading to improvement while other patients find the relief when the eye disease progresses to total blindness[2]. Treatment with antipsychotic and anticonvulsant was mostly unsatisfactory[6,12]. Various nonpharmacological interventions had been recommended such as reducing social isolation, engaging in personal hobbies and improvement of environmental condition especially withlighting at home are beneficial[13].
Hence, discussion of these phenomena with the patient is vital as assurance of their harmless nature will ease their anxiety and concern. At present, the best form of treatment appears to be reassurance, empathy and counseling about the condition. Moreover, the awareness of this syndrome among medical personnel[3,14] and ophthalmologists is vital as most visually impaired patients would often present to the ophthalmic clinic first.
In conclusion, with regard to such a group of patients especially elderly patients that possess the insight into the unreality of what they are seeing with a deteriorating vision, ophthalmologists should therefore raise the suspicion of possible Charles Bonnet syndrome. Accurate diagnosis is critical as incorrect diagnosis could lead to sufferers being referred to inpatient psychiatric care, which may be very distressing and is unlikely to reduce or eliminate the occurrence of hallucinations.
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